I tried a challenge like this once before and started with foraging (not a good idea - your method of starting with fishing so you have money to upgrade tools and food for energy is much better). I got bored of that before actually finishing foraging, but your post inspired me to give the challenge another go.
I used this min-max guide (
https://github.com/Zamiell/stardew-valley/blob/main/Min-Max_Guide.md#spring-2) with slight modifications (ie no picking up foragables) to help level fishing as fast as possible and picked the forest farm for the extra 200XP every day from the 8 renewable hardwood stumps, plus the chance of forageables spawning on the farm. Like you, I upgraded the tools I needed for the next skill I planned to work on whilst doing the previous skill. I didn't allow myself to gain any XP in the next skill until the previous one was level 10, but if I reached level 10 before 2am I could immediately start on the next skill. This became a problem during my foraging section when my bat cave was blocked by a stone I wasn't allowed to break as it would give me mining XP.
I wanted to complete the community centre in good time, so decided to try: Fishing, Foraging, Mining, Farming, Combat. The plan was to finish mining before the end of summer (having planted some summer crops earlier in the season and watered them by hand whilst working on mining) so I could get all the summer CC crops and would only need the spring ones in year 2.
On my first attempt I maxed fishing late on spring 8, foraging on summer 1, mining on summer 14 and got to farming 5 on summer 16 (I'd planted a batch of melons and hot peppers at the start of the summer intending to get to level 6 and unlock sprinklers as soon as I completed mining, but hadn't allowed enough margin for crows).
That first run taught me the following:
- Fishing in the river on rainy days is great for money (catfish) but gives less XP than fishing in the mountain lake as it's so much harder to get perfect catches, particulalry at lower fishing levels. It's worth fishing in the rain on day 3 as you need money to start upgrading tools, but is probably better to stick to the lake after that unless you're killing time before Clint opens and you can upgrade a tool. (The lake fish are much easier to get perfect catches on, particularly at lower levels of fishing skill.)
- During the fishing section, it's best to buy the ore and coal needed for the next tool upgrade when you pay for the previous tool upgrade so you can have the bars smelted and ready to go. I wasted so much time running around town on upgrade days!
- With the exception of the first one, it's generally better to sell artifacts and geode minerals rather than donating them to the museum whilst money is tight.
- I could have just used the chair trick to access my bat cave (I realised this about 1 in-game day after finishing foraging)
- Planting tree seeds on the farm was great (leave the stumps on the farm to start with so they continue to generate seeds), but I should have spaced them further apart so that if there were multiple stage 4 saplings close together they could all grow into mature trees on the same night.
- Planting mahogany seeds on the farm was not worth it. They grew way too slowly, and they sell for 100g each so I would have been better off selling them.
- Breaking boulders doesn't give mining XP, so can be done before you start mining to get stone to start on farm buildings (or have a stockpile ready for staircases)
- My method of reaching level 80 as fast as possible and then checking floors 45, 55, 65, 75 for gem nodes (particularly diamonds) before getting gold (and fibre) from floor 80 worked well, but the chance of a 150 XP diamond node increases as you go lower in the mines so it would be better to reach floor 115 as soon as decent luck allows to increase the number of floors you can quickly check with the elevator. The 80+ floors also have the chance of 80 XP ruby and emerald nodes which are also very useful. (Technically the fastest way is probably to keep using the elevator to check for gem nodes, but it gets very dull! Adding the trip to floor 80 adds just enough variety to stop me getting too annoyed with the elevator thing.
- Allow more redundancy when planting crops! Also think about where to place mixed seeds so that any corn and hot peppers aren't in a spot where you'll want to place a sprinkler after unlocking them.
- Try to get farm buildings started sooner and buy animals in time for them to mature by the time mining is complete (or earlier in the case of chickens, since they will fill up the coop with eggs that you can grab on day 1 of farming).
- I completed mining faster than I'd anticipated and had to wait a few days for my melons to be ready, so I knew on the second try I needed to plant my summer crops immediately.
With those lessons in mind, I had a second attempt and managed to reach fishing 10 by about 11.40am on Spring 8 (just enough time to collect the steel axe and chop the renewable stumps on my farm before returning the axe to Clint to upgrade it to gold). I had some good luck with my Spring foragables and was able to plant more spring seeds than on attempt 1 (although I did get fewer spring onions), and was able to reach foraging 10 and get started on mining on Spring 28. I planted my mixed seeds and lots of melons on summer 1 and watered them daily whilst levelling mining. On Summer 5 I bought 8 chickens, 4 cows and 1 milk pail to fill the farm buildings that were built at the time.
In a stunning piece of luck on Summer 10, I found a mystic node in the mines and got a prismatic shard! That was really helpful when it was time to level combat, because I was able to get the galaxy sword and use it to slay monsters without reaching the bottom of the mines and making the monsters harder to kill. (I didn't even know mystic stones could spawn in the regular mines, but the wiki says they can appear from floor 101 and are more likely at lower floors and with higher luck.)
I completed mining at 4.30pm on Summer 12 and returned to the farm to tend the animals and harvest the wheat, radishes and hot peppers from the mixed seeds. That got me to farming 3, and most importantly meant that I could place scarecrows once I'd harvested the melons on Summer 13. I then bought enough melons (with a few other CC crops I forgot to buy at the start of summer) to reach farming 10. I didn't quite get them all planted on the 13th, but by the 14th everything was planted. Whilst waiting for the melons to grow I caught the summer fish and collected gems, geodes and fibre from the mines whilst upgrading my farm buildings further, buying more farm animals and giving a few birthday gifts. At some point I finally ran out of the wood I'd chopped during my foraging stint and had to actually cut down some of the trees that had grown from the seeds I planted during the foraging section.
On Summer 26 I reached farming 10 and took my galaxy sword to the mines to start on combat. I'd already traded most of my diamonds with the desert trader to get triple shot espresso which I used to increase my speed. (In hindsight I should have started doing this earlier, either with espresso or buying coffee from Gus to drink when gem nodes were a long way from the elevator during my mining section). My general strategy was to check floors 45, 55, 65, 75, 85, 95, 105 and 115 for any monsters close to the elevator or a clump of several monsters further away. On the first day I also checked 5, 15 and 25 until I'd killed 10 green slimes to unlock the adventurer's guild. Each day I also checked floors 41, 51, 61, 71, 81, 91, 101 and 111 for any infested floors. My reasoning for including the ice floors was that I wanted to complete the dust sprite monster slay goal to increase item drops, but I actually ended up finishing the void spirit goal first. I've never actually used the savage ring before, but the speed boost after slaying a monster made it much faster to get to the next monster or back to the elevator so I should have focused on completing that first.
With the help of a slime floor on 101 on fall 7 (big red slimes give 21 XP and the little ones 10 XP, plus floor 101 is quick to get back to the entrance if the last slime dies in an unhelpful place so it was probably one of the best infested floors I could have had), I reached combat level 10 on Fall 8, having spent some time planting wheat in late summer and then pumpkins and other fall crops on fall 1 and 2.
I'm now tempted to try the whole thing again and see if I can optimise things further. During the farming part of my second run I read about geode placement and learned that within a particular save file geodes spawn in the same spot on a particular floor regardless of the day - so if you can find a geode within 1 square of the elevator you can very quickly amass a collection of geodes. In my particular save file I had magma geode spots 1 and 2 spots right of the elevator on 105 and a frozen geode spot right of the elevator on 45. The downside of collecting geodes this way is it does get very repetitive, but it might allow me to do switch things up and do mining second, farming third (using money from geodes and gems to fund farm expansion) and then foraging and combat. That would allow me to get the spring CC crops and therefore get the greenhouse in fall. I could then use the desert trader to swap winter seeds for spring seeds, grow them in the greenhouse and complete the CC in year 1. (Or alternatively reach farming 10 before the end of spring so I can pick up the spring forage, but that seems fairly unlikely!)
